1.8 Genomic Sequencing

Question 1

what happens during genomic sequencing?

Answer 1

the sequences of nucleotide bases can be determined for individual genes and entire genomes

Question 2

what reasons are there for sequencing genes?

Answer 2

• to determine the function of genes
• to look for differences in individuals with disease
• to find out the mechanism of action o disease-causing genes

Question 3

what reasons are there for sequencing entire genomes?

Answer 3

• you can find all coding sequences which gives us an insight into conserved areas
• allows us to compare genomes (within and between species)
• allows us to find disease-causing alleles
• allows us to find information on expression sequences
• can be used as an important model organism for research

Question 4

what happens once the genomes have been sequenced?

Answer 4

• genomes between organisms (of the same or a different species) can be compared
• computer programs can be used to identify base sequences by looking for sequences similar to known genes

Question 5

describe ‘phylogenetic and phylogeny’

Answer 5

Phylogenetics is the study of evolutionary history and relationships.

A phylogeny is a proposal of how organisms are related to by their evolutionary history. It is based on the evidence that all living things are related by common descent.

Question 6

starting with cells, what is the sequence of events in the evolution of life?

Answer 6

• cells
• last universal ancestor
• prokaryotes
• photosynthetic organisms
• eukaryotes
• multicellularity
• animals
• vertebrates
• land plants

Question 7

describe ‘molecular clocks’

Answer 7

Molecular clocks are used to show when species diverge during evolution.

DNA sequences are compared and the number of differences in the sequence data between species is used to indicate the time of divergence from a common ancestor.

The greater number of of differences between species sequence data, the greater the length of time since divergence.